Self-locking medicament capsule



sept. 3, 1968 J OGLEVEE ET AL 3,399,803

SBLF-LOCKING MEDICAMENT CAPSULE Filed Oct. 11, 1966 HAROLD J. OGLEVEE RALPH E. MOTTIN INVENTORS BY M15, Mm

ATT Y- United States Patent 3,399,803 SELF-LOCKING MEDICAMENT CAPSULE Harold J. Oglevee, Grosse Pointe Woods, and Raiph E.

ABSTRACT OF THE DISCLOSURE A separation-resistant hard shell capsule adapted for fabrication on automatic dip molding machinery is provided having a cylindrical telescopically-joined coaxial cap and body. The inner wall of the cap has an inwardly extending circumferential ridge defining an opening small enough to allow the body to enter into a partly locked position in the cap. The opening is large enough, however, to allow the body to enter into a fully locked position in the cap. Optionally, the body has a circumferential groove located for matching contact with the ridge in the fully locked position. The capsule can be made and filled in large numbers at normal production rates on conventional machinery.

Summary and detailed description This invention relates to hard shell medicament capsules of the type having a cap part and a body part adapted to telescope together to provide a container for substances such as pharmaceutical preparations intended for oral administration. More particularly, the invention relates to capsules of the kind described which can be filled and joined on high speed machinery and which in finished form resist separation of the cap and body parts.

The conventional gelatin capsule consists of a tubular or cylindrical cap part closed at one end with the opposite end opento telescopically receive a closely fitting body part of like conformation. The two matching parts for this capsule are manufactured inlarge numbers on automatic machinery by dipping stainless steel mold pins into aqueous gelatin, drying the gelatin shell on the pins, stripping the dried shells from the pins and trimming the resulting capsule parts to the required length. The mold pins are designed to have a uniform taper or candle-shape in order to avoid suction or other resistant force when the capsule part is stripped from the pin. As an intended consequence of the taper in the mold pin, the resulting cap and body likewise have a taper and this advantageously provides a wedging fit between the cap and body when they are later joined together in the finished capsule. The wedge fit is usually sufficient for ordinary purposes, especially in cases where the capsule is sealed with a surrounding band or filled with powder.

Referring further to the manufacture of capsules, the mold pins which are used tend to stick under constant use and therefore must be lubricated with a film of oil prior to dipping. Because of the need for lubrication, the mold pins are designed to have a conformation which assures an even distribution of the lubricant so that calized buildup of oil and the attendant weakening of the capsule wall in the area are avoided. In this connec tion it is necessary for the mentioned stripping from the pins to be fast and effective. The operation on a single machine is done several hundred thousand times a day. Thus, any impediment to the smooth withdrawal of the capsule part from the pin is to be avoided if at all possible. It will be understood that if the dried capsule part does not strip properly from the pin, the unstripped pin ordinarily goes undetected and passes through the next cycle of dipping, drying, etc. This causes loss in producice tion and in extreme cases can cause machine damage. Subsequent to the stripping and trimming steps, and in fact as a component part of the motion past the trimming knives, the cap part and the matching body part are joined together. The joining is only partial, that is in a temporary fit suitable for shipping and for ultimate separation, filling and finishing by the manufacturing consumer. To fill the empty capsules, the caps and body portions are uncapped in automatic machinery, filled with the desired medicament and are then rejoined by application of pressure. As an optional step, the capsules, either filled or empty, are processed through printing machinery which imprints a legend on the cap and the body part. One of the finishing steps sometimes employed is polishing. This is commonly done by tumbling the filled capsules with granular salt to rid the capsules of surface powder. Prior to shipping, the capsules are counted by means of electronic counters, shimmy boards, etc. Also, in the filling, polishing, printing and counting operations, the joined capsules are handled and transported by vibration or gravity drop in feeder bowls, conveyors, chutes, ramps, etc. The treatment received by joined capsules prior to shipment is therefore rigorous. During shipment, the fate of the capsules is unpredictable but physical stresses and extremes of temperature and pressure are often encountered. For example, during air shipment it is not uncommon for the capsule to be subjected to high altitude vacuum and temperature.

It occasionally happens that an empty capsule will become wedged too far thereby making it difiicult for the customer to uncap the capsule properly for the filling operation. An even more serious difficulty arises when after rejoining the cap on the filled body the cap is only loosely seated so that the cap separates and medicament is lost from the capsule. In such a case the consequences are undesirable from several standpoints: for example, the loss of medicament represents a departure from the label claim. Also, the loose medicament can interfere with production particularly in the printing operation. Other instances of this type will be obvious.

It is therefore an object of the present invention to provide an improved hard shell gelatin cap-and-body capsule which can be readily manufactured on high speed automatic machinery and which in joined form filled with medicament satisfactorily remains intact without unintended loosening or dislodgement of the cap, loss of medicament, etc.

Another object of the invention is to provide a selflocking hard shell gelatin capsule which may be placed in a partly capped position prior to filling and which will remain in this condition without accidentally becoming sealed.

Still another object of the invention is to provide a capsule of the kind described which after filling with a medicament can be readily sealed simply by pushing the capsule parts together, without damage to the capsule.

Yet another object is to provide hard shell gelatin capsule parts of a type which in the molding process can be readily stripped from the mold pins.

Other advantages, objects and features of the invention will be apparent from the following description and the accompanying drawing in which:

FIG. 1 is a side view of an assembled capsule of the invention;

FIG. 2 is a cross-section of part of the capsule of FIG. 1 showing the capsule in completely closed position;

FIG. 3 is a similar view of the capsule in partly closed position;

FIG. 4 is a partial cross-section of a preferred embodiment of a capsule;

FIGS. 2a and 4a are enlarged sectional views of portions of FIGS. 2 and 4;

FIG. is a side view of a capsule mold pin; and

FIG. 6 is a plan view of a port-ion of the mold pin of FIG. 5.

According to the invention there is provided a capsule 10 as illustrated in FIG. 1 having a cap 11 and body 12 with closed ends and 24, the parts being readily molded, stripped, etc., on high speed machinery and assembled easily, as desired, in either locked or semi-locked position. The cap 11 has a circumferential groove 17 or constriction into which the body 12 can be wedged into locked position to provide a durable seal against dislodgement from causes normally encountered in handling and shipment. For purposes of the invention, the capsule parts are conveniently made of gelatin since gelatin can be safely ingested and has the desired plastic qualities, structural properties, etc. It will be realized that other materials having the same desired properties can, for purposes of the invention, be substituted in whole or in part for gelatin.

The cap 11, in greater detail as seen in FIGS. 2 and 3, has an inner wall 13 and an outer wall 14 with an open end 16. On the inner wall 13, opposite to the groove 17 on the outer wall 14, is a circumferential ridge 18. Ridge 18 has a generally triangular cross-section defined on the inner surface by bevels 19 and 21 which meet at the apex 20. The closed end 15 is preferably rounded or hemispherical but the shape is not critical. If desired, the cap end can have other shapes. The inner surface 13 proceeding from the open end 16 to the line 22 which is the shoulder line, has a slight narrowing diametral taper of the order of 0.010 inch per inch, exclusive of ridge 18. In FIG. 3, the cap and body are shown in partly closed or semilocked position with the open end 25 of the body advanced to the leading bevel 19 of the ridge 18. The body has a groove 18a which matches the ridge 18. Groove 18a has a leading bevel 19a and a trailing bevel 21a which join at apex a. In FIG. 2 the cap and body have been pressed together from the partly closed or semi-locked position into the fully closed, locked position. In the latter position ridge 18 and body groove 18a are in matching fit with their respective bevels and apexes in direct contact as seen in FIG. 2a. In this position the open body end has advanced into the cap to a point just beyond the shoulder line 22. The body, like the cap, is tapered in the same degree and in the direction from its open end to its closed end. The body taper and the body dimensions in relation to the taper and dimensions of the cap are such as to provide an ample entrance of the body into the cap and yet afford a snug fit in the area where the body end is advanced to the semi-locked position. In this position the cap and body desirably are wedged together and will not separate under conditions normally encountered prior to filling. More important, however, the two parts resist accidental locking, partly because of the opposing diametral taper mentioned, partly because of the impinging circumferential ridge 18, and also because of the restricted cross section above the shoulder line 22.

In another embodiment of the invention, as seen in FIGS. 4 and 4a, the cap has the same configuration with the circumferential ridge 18, as described above, and the body has the conventional form which lacks the circumferential groove 18a. This embodiment is quite similar to the above-described embodiment in that it otherwise has the same component parts and provides both the semilocked and locked positions; it has an advantage in that it does not require special body pins for its manufacture. The locking fit in the ridge-and-groove area as illustrated in FIG. 4a makes primarily for a wedging contact between the apex 20 of the ridge 18 and the apex 20a of the groove 18a. In other words, the contact of the outer surface 14 of the body with the bevels 19 and 21 of the ridge 18 tends to be discontinuous with maximum locking pressure at apex 20. The result is that this embodiment of the invention ordinarily provides a firm lock against any relative movement of the cap and body in contrast to the first described embodiment (FIG. 2a) wherein the cap and body are held together in what may be termed a loose lock. The loose lock is advantageous because it provides a permanent seal against accidental separation and yet the capsule can be opened intentionally, if desired, with a minimum possibility of spilling and losing the contents. It is found that the loose lock outperforms conventional capsules with respect to sealing, while at the same time the ease with which the capsule can be separated intentionally is quite perceptible. The reason for the loose lock is believed to be that the locking portions of the ridge 18 and'groove 18a including the bevels and apexes are under a minimum of distortion, if any. This makes for greater durability of the conformation of contact between the cap and body. The firm lock provided by the embodiment of FIG. 4a, however, surprisingly and in contrast is found to become less durable with passage of time, upon aging. This is believed to be due to the fact that the locking portions in this area are under stress so that the capsule in response undergoes plastic deformation to a steady state having the form more nearly as shown in FIG. 2a in which state the lock desirably represents a condition of minimum distortion.

A further advantage of the capsule parts of the invention is the relative ease with which they strip from the pins on high speed, modern, automatic machinery of conventional design. FIG. 5 shows a mold pin 26, supported on a spindle 27, of the type used for producing capsule parts of the invention. As will be appreciated, the pin 26 can be used for producing either caps or bodies depending on the particular dimensions required. Thus, for either case the pin has a head portion located above the shoulder line 22 and is otherwise generally cylindrical in shape. The head portion as shown is substantially hemispherical; other shapes can be used depending on the particular shape desired in the finished capsule part. Spaced below the shoulder line is a circumferential groove defined by the bevels 29 and the fiat surface 20. The dotted line 28 below the groove represents the cutting line where the capsule part after clipping of the pin in gelatin solution, drying and stripping the part from the pin is cut.

For the production of #1 capsules of the invention, the cap pin of the type shown suitably has the usual dimensions of a #1 pin. The pin is modified, however, in that it has the circumferential groove and the groove is located a sufficient distance from the shoulder line 22 so that the resulting molded cap will have a continuation in the taper between the ridge 18 and the shoulder line. The distance is not believed to be critical but should ordinarily be about .050 to .060 inch from the shoulder line to the center of the groove. The profile of the groove, as seen in FIG. 6, indicates more clearly the contour provided by the taper of the pin 26 with the two bevels 29 and the flat surface 30. It is found that the diametral constriction for the groove of a #1 mold pin should be about .003 to .005 inch. A lesser constriction is not satisfactory because body parts tend to lock accidentally in caps having an insufiicient constriction. Also, the bevel angle A is somewhat critical. This angle, formed between an imaginary vertical line and the bevel 29 should be about 3 to 5 or higher up to about 10. Larger angles are to be avoided since the resulting capsule parts are unduly difficult to seal into locked position. In fact, if the pressure required to seal the capsule is excessive, under the conditions applying in large scale filling operations, there will be an unduly high number of capsules with punched ends. Referring to the contour of the groove, FIG. 6, it is not essential for purposes of the invention for the pin to have the fiat surface 30; as a corollary it is not essential for the ridge 18 of the cap or the groove 18a of the body to have the fiat surface. In other words, while this flat configuration is preferred, the two bevels 29 can directly intersect in a generally obtuse angle without the intermediate straight or fiat surface 30.

Referring further to the general mold pin dimensions, for a #1 cap the shoulder line 22 will ordinarily be about .090 to .099 inch and the cutting line 28 about .440 to .465 inch from the top of the pin. At the cutting line the diameter will be about .240 to .250 inch and the taper conveniently about .010 to .015 inch per inch to the shoulder line. For a #1 body, the cutting line 28 will be about 0.640 to 0.670 inch from the top of the pin, and the center of the groove about .050 to 0.060 inch, from the cutting line. The taper will be the same as the cap taper and the groove dimensions will preferably match those of the cap. Preferably also, as specified below, the dimensions should be selected so that when the cap and body are in the locked position the ridge and the groove (where present) match and the open end of the body extends inward just beyond the shoulder line to the point where a wedge fit is thereby generated.

It will be realized that the molding process confers the exterior configuration of the pins to the inner surfaces of the respective caps and bodies produced.

The thickness of the capsule part produced varies depending on various factors but on the average is about .003.005 inch. Once the gelatin has set up on the pins and has been dried by application of heat and forced air, the resulting relatively thick and rigid capsule part, as is known, is quite difiicult to strip from even the conventional lubricated pin. It is indeed unexpected therefore that the capsules of the present invention, fabricated with an inwardly extending circumferential ridge in matching engagement with the groove of the mold pin, can be successfully stripped without damage, at high speed and in large volume. It is even more surprising that the stripping takes place, if not with less efiort, with the same effort as that involved in conventional stripping. One would have thought that the groove in the pin would seriously impede the stripping of the molded part especially where the groove constitutes the exact opposite kind of taper or reverse taper to the type of releasing surface thought to be desirable for reliable stripping. The groove in the pin and the resulting capsule part would also have been thought to be objectionable because of the tendency at the groove for build-up of lubricant and consequent imperfect mold elfect in the groove area thereby resulting in a sub-standard wall thickness and hence a weakened capsule. It has been found, however, that the quality of the capsules of the present invention is in this regard unimpaired.

The preferred embodiment described above wherein the open body end extends inward past the cap shoulder line advantageously provides a self-regulating cooperative locking action with the lock obtained by the cap ridge and body. In this embodiment the extent of wedging of the body end 25 into the cape end 15 can desirably be varied, owing to the flexibility of the parts in response to a closing pressure, and this variability advantageously can be relied on as a safety factor to offset any dimensional variation from capsule to capsule with respect to the distance from the cap shoulder line to the locking cap ridge and body groove. The subject contacting action of the cap and body ends 15 and 25 thereby serves not alone to limit the position of the cap with respect to the body but also to enhance the locking action of the cap ridge by wedge means separate from the latter ridge.

While in the foregoing specification embodiments of the invention have been set forth in detail, it will be realized by those skilled in the art that considerable variation in such detail can be made without departing from the spirit of the invention.

We claim:

1. A separation-resistant hard shell capsule adapted for fabrication on automatic dip molding machinery, having a generally cylindrical telescopically-joined coaxial cap and body each having side walls and an open end and a closed end, the inner wall of the cap having a circumferential annular beveled ridge extending inward from the wall, the contour of the ridge being triangular and including low angle leading and trailing bevels having a bevel angle up to about 10 and an optional flat surface between the bevels, the ridge defining an opening small enoughto permit partial entry of the body into a partly locked position in the cap and yet large enough to permit full entry of the body into a fully locked position in the cap.

2. A capsule according to claim 1 wherein the body has a circumferential groove in matching contact with the ridge in the fully locked position.

3. A capsule according to claim 1 wherein the open end of the body engages the closed end of the cap in a wedge fit when inserted in the fully locked position.

References Cited UNITED STATES PATENTS 525,845 9/1894 Hobbs 16783 2,549,644 4/1951 Silverman 2201 2,718,980 9/1955 Strom 220- JAMES B. MARBERT, Primary Examiner. 

